Boston Mayor Thomas Menino said he won’t back down from his stance against Chick-fil-A and its anti-marriage equality stance, but acknowledged Thursday he cannot prevent the fast-food chain from opening a new franchise across the street from City Hall.

Late last week, Menino vowed to block Chick-fil-A from opening a restaurant near the city’s “Freedom Trail,” a response to comments by the chain’s president that gay marriage is “inviting God’s judgment on our nation.”

Thomas Menino

“There is no place for discrimination on Boston’s Freedom Trail and no place for your company alongside it,” Menino wrote in a letter to Cathy.

On Thursday, however, Menino backed off threats to interefere in Chick-fil-A’s opening. “I can’t do that. That would be interference to his rights to go there,” Menino said.

“The government can regulate discrimination in employment or against customers, but what the government cannot do is to punish someone for their words,” said Adam Schwartz, senior attorney for the ACLU of Illinois.

The ACLU “strongly supports” same-sex marriage, Schwartz noted, but said that “if a government can exclude a business for being against same-sex marriage, it can also exclude a business for being in support of same-sex marriage.”

Dr. Jonathan Turley, a constitutional law expert and professor at the George Washington University Law School in Washington said that Menino’s intentions raises “serious” constitutional concerns.

“It’s also a very slippery slope,” Turley said an email to LGBTQ Nation late Friday. “If a City Council started to punish companies because of the viewpoints of their chief operating officers, that would become a very long list of banned companies.”

Also this week, San Francisco Mayor Edin Lee jumped into the debate, and tweeted, “Closest #ChickFilA to San Francisco is 40 miles away & I strongly recommend that they not try to come any closer.”

Lee stopped short of threatening to block any future restaurant openings.